The overall objective of this project is to develop a detailed molecular level understanding of metal binding in transferrin (TF) proteins. This objective will be pursued primarily by developing and applying a combination of laser based spectroscopic tools in conjunction with techniques to trap or isolated both equilibrium and non-equilibrium forms of the protein. Site and residue specific conformational probing of Tf will be explored using primarily ultra violet and visible resonance Raman spectroscopy and a relatively new lanthanide (III) based vibronic luminescence spectroscopy. These vibrational spectroscopies will be supplemented with absorption and fluorescence studies. Objectives of this part of the project include identifying spectroscopic signatures both for functionally distinct conformations of Tf and for functionally important local degrees of freedom. The intent is to be able to probe the local interactions as a function of changes in the global conformations. Spectroscopic and kinetic characterization of specific conformations of Tf will be accomplished with the addition of a new porous sol-gel based encapsulation method of trapping and locking in of specific protein structures. An emphasis will be placed on probing the apo and metal bound forms of both the open and closed confirmations of Tf as a function of pH, anions, metal ligands (chelators), transferring receptor, site-specific mutations and metal cations.